Wedge bolt with slotted end of elliptical cross-section



Dec. 13, 1955 w. R. PENMAN WEDGE BOLT WITH SLOTTED END OF ELLIPTICALCROSS-SECTION Filed Oct. 25, 1951 INVENTOR 9 h/zlter IZ. Penlluuv.

BY 2f@ United States Patent O WEDGE BOLT WITH SLOTTED END F ELLIPTICALCRSS-SECTION Walter R. Penman, Lebanon, Pa., assigner to Bethlehem SteelCompany, a corporation of Pennsylvania Application October 25, 1951,Serial No. 253,128

2 Claims. (Cl. 852) My invention relates to improvements in wedge boltswith slotted ends of elliptical cross-section and accessories.

By means of proper roof bolting, it is possible to eliminate at least aconsiderable part of the risk of sags and falls of overlying strata ofrock and coal otherwise inherent in ordinary mining operations.

One object of this invention, therefore, is to provide a mine roof rodwhich will develop maximum grip and holding strength when in place underload.

Another object is a roof rod which will resist rotation while a nut isbeing threaded thereon.

Still other objects, purposes and advantages of the invention willappear hereinafter in the specification and drawings and in the appendedclaims.

In the annexed sheet of drawings:

Fig. 1 is a vertical cross-section of a mine entry, illustrating oneapplication of my invention with a continuous roof support;

Fig. 2 is a broken side elevation of a mine roof rod, showing the lowerend threaded to engage a nut and the upper end corrugated and slotted toreceive an expansion wedge;

Fig. 3 is a top plan view of the mine roof rod of Fig. 2, and showingthe generally elliptical form of the upper end of the rod;

Fig. 4 is a side detail view of the upper end of the rod, rotated 90from the side shown in Fig. 2;

Fig. 5 is a horizontal transverse section of an ordinary round rodhaving a smooth outer surface on the upper end, showing the limitedbearing area of a split round rod against the periphery of the roundhole within which it is expanded by the wedge;

Fig. 6 is a transverse horizontal section of the expanded ellipticalupper end of a rod having a limited number of rounded longitudinalcorrugations, four on each side being shown, illustrating the enlargedarea of peripheral contact with the same hole;

Fig. 7 is a transverse horizontal section of the unexpanded ellipticalupper end of a rod having a larger number (shown as seven) ofsharp-toothed longitudinal corrugations;

Fig. 8 is a transverse horizontal section of the upper end of the rodshown in Fig. 3; and

Fig. 9 is a transverse horizontal section of a rod having a smoothelliptical outer surface on its slotted upper end.

Referring more particularly to Fig. 1 of the drawings, the referencenumeral 1 indicates a mine entry or other passageway through a coal vein2 forming side walls or pillars 3 and having overlying strata 4 of rock,slate and the like which form a roof 5 for the passageway. Rails 6 onrail ties 7 are provided on the oor 8 for the movement of mine cars ormachines in understood manner. Steel roof ties 9 or the like supply beamICC strength and reinforcement to the mine roof 5, against which theyare held by nuts 10 bearing against flat washers 11 or angle washers 12,said nuts 10 being threaded onto the lower ends 13 of round rods 14 rmlyanchored in holes 21 somewhat larger than said lower rod ends 1?:drilled in the overlying strata.

In Fig. l a pair of rods 14 are shown as driven vertically upwardthrough suitable holes in the roof tie 9, with two other rods extendingdivergingly outward and upward through similar holes at each end of theroof tie 9 into the rock above the pillars 3. Other arrangements orcombinations of rods with other members Y are obviously possible,however.

The lower ends 13 of the rods 14 are externally threaded as at 15 toreceive the nuts 10. The upper ends 16 of the rods are substantiallyelliptical in crosssection, with their hole-engaging outer surfaceshaving a radius of curvature substantially equal to or greater than theradius of the hole, and are longitudinally slotted as at 17 throughtheir major axes. Said outer surfaces may be provided with longitudinalcorrugations, either numerous and sharp-edged as at 18 (Fig. 7) or fewerand more rounded as at 19 (Fig. 8), o1' even without corrugations, asat20 (Fig. 9), the last-mentioned form tending perhaps to be slightly lessresistant to applied torque than the others. Comparison of Figs. 5 and 6will illustrate the increase in bearing area against the hole madepossible by an expanded rod surface which is elliptical instead ofround, with rods of equal weight.

To expand the slotted upper ends 16 of the rods 14 against theperipheries of the holes 21, any of conventional flat-pointed wedge maybe satisfactorily employed.

Although I have thus described my invention in considerable detail, I donot wish to be limited narrowly to the exact and specific particularsdisclosed above, but I may also use such modications, substitutions, orequivalents as are included within the scope and spirit of the inventionor pointed out in the appended claims.

I claim:

l. A mine roof rod, comprising a rod having an externally threadedportion at one end and an opposite end portion of substantiallyelliptical crossasection, said substantially elliptical portion beinglongitudinally slotted through its major axis and adapted to be expandedin a circular hole in the mine roof, the radius of curvature of thehole-engaging surface of said elliptical slotted end portion being atleast equal to the radius of the hole,

2. A mine roof rod, comprising a rod having an externally threadedportion at one end and an opposite end portion of substantiallyelliptical cross-section, said substantially elliptical portion beinglongitudinally slotted through its major axis and adapted to be expandedin a circular hole in the mine roof; the radius of curvature of thehole-engaging surface of said elliptical slotted end portion being atleast equal to the radius of the hole, said hole-engaging surface beingfurther provided with a plurality of external corrugations; whereby saidrod is characterized by great holding power and resistance to rotationwhen expanded in a circular hole.

References Cited in the le of this patent UNITED STATES PATENTS 419,018King et al Jan. 7, 1890 660,566 Gage Oct. 30, 1900 710,216 Schmidt Sept.30, 1902 1,229,287 Kennedy June 12, 1917 1,251,566 Pigott Jan. 1, 19181,349,998 Aylward Aug. 17, 1920

